Take your time. Self-respect sells.

Speak deliberately. If you see from a puzzled or doubtful look on the prospect’s face that any thing is not quite plain to him, stop and make it plain. Take time enough to explain each point thoroughly. Whenever you make a statement that is open to question, be sure to get his assent to it before you proceed. If he will not assent to it exactly as you make it, modify it until he does. Get him to assent in some degree to every proposition you make, so that when you get to the general result he cannot go back and disagree with you. Don’t do this, however, as if you were trying to corner him, but with a simple desire to reach a reasonable basis of argument.